This invention relates to electrical connectors and more particularly to an electrical connector which has an extended lifetime for production testing of electrical circuits having a fixed set of electrical contacts. The electrical connector of the invention connects the circuit to an automated testing device. A commonly used connector which is attached to printed circuit boards is of a type which has blades which extend for insertion into some form of pressure contact in a mating connector. An example is the female connector provided with a commercially available test set where the connector consists of individual "tuning fork" contacts which mate with the spade type terminals of the connector attached to the printed circuit board. This type of female connector has an advertised lifetime of 500 cycles which lifetime is governed primarily by the wiping contact wear on the tuning fork.
The limited life of this standard female connector requires that the connector be changed every few days. This requirement results in considerable labor costs and test set unavailability. Additionally, and perhaps more important, before the standard connector actually fails, random intermittent problems arise which are difficult to isolate and result in increased trouble shooting labor costs.
Another undesirable feature of existing test set connectors is that the module to be tested is inserted manually. The difficulties of manual insertion limit the test set capability to less than 1000 units per eight hour shift because the high insertion and removal forces result in operator fatigue and possibly even hand injury. Hand insertion also results in the operators tending to "wiggle" the module when inserting and removing the module from its test connector which results in pin damage.
Attempts to replace the standard tuning fork type of connector contacts have been made using commercially available "Pogo Pins". The pogo pins have spring loaded plungers which contact the ends of the module terminals upon insertion. The primary advantage of this concept is that insertion and removal force is substantially less than for the tuning fork connector which results in decreased operator fatigue and module connector damage. The disadvantages with the pogo pin type of connector is that the low axial plunger force (less than 2 ounces) results in high and nonrepeatable contact resistance. Further, the pogo pin design uses a plunger spring and barrel which design results in a higher resistance path. The density of the pin components on the connector is such that small pin components are required. Therefore, they are easily bent and damaged.
Another approach for a test set connector works on the principal of inserting the module terminals into a receptacle followed by clamping the terminal pins by turning a dial or moving a lever. Although this technique minimizes connector wear and has low insertion/removal forces, it is difficult, if not impossible, to attain a low contact resistance. The absence of contact wiping coupled with low clamping force because of size constraints makes this approach unattractive.
It is therefore an object of this invention to eliminate the deficiencies of the prior art connectors by providing a connector which has low contact resistance, which produces minimum operator fatigue, and which has an extended lifetime requiring little "downtime" for maintenance.